Combination pulverizing and classifying machine



g- 5, 1952 N. H. ANDREWS 2,605,971

E COMBINATION PULVERIZING AND CLASSIFYING MACHINE Filed Aug. 3," 1949 -2 SHEETS-SHEET 1 a M68 43 I7 27"- Snventoi: Nam/ 000 ANDREWS Gttorneg 8- 5, 1952 N. H. ANDREWS 2,605,971

COMBINATION PULVERIZING AND CLASSIFYING MACHINE Fi led Aug. 5. 1949 2 SHEETS-SHEET 2 fig., I Snnqitor NORWOOD H. ANDREWS Patented Aug. 5, 1952 COMBINATION PULVERIIZING AND CLASSIFYING MACHINE Norwood H. Andrews, Moorestown, N. J assignor, by mesne assignments, to Freeport Sulphur Company, New York, N. Y., a

Delaware corporation of Application August 3, 1949, Serial No. 108,266 8 Claims. (01. 24139)' This invention relates in general to a device for classifying a product of pulverization andmore particularly to a type thereof in which a partially comminuted material may be further reduced in size while being classified and selectively carried off to a collector system.

The combination pulverizing and classifying machine to which this invention relates, hereinafter referred to as the classifier, is an improve ment upon the device disclosed in the Andrews and Willoughby Patent No. 1,953,058. The separator portion of said device has been foundin practice to operate unsatisfactorilyunder certain conditions. For example, since it is usually desirable to collect only uniformly small particles, called fines, the gas within the separator must circulate at a very high speed in order to provide a centrifuge of sufficient strength to prevent the large particles from being entrained with said small particles or fines as they leave said separator. However, said high speed rotation of said gas not only causes the large, or oversize, particles to be centrifuged out of the rotation gas against the cylindrical wall of the separator but also causes a substantial quantity of the fines to do likewise. As the large particles are pulled down said wall by gravity, said centrifuged fines, which would otherwise be carried off to the collector, may also be carried downwardly with said large particles. This mixture of large and small particles drops into the bed of partially comminuted material and the bottom of the separator.

This situation becomes more clear when it is remembered that after the usual grinding operation, particularly of the impact type, the particles of shattered material are not all uniformly large and uniformly small, but rather are ofa wide gradation of sizes. In present equipment, the separation of extreme heavies and extreme fines is accomplished satisfactorily, but there are large quantities of materials of borderline sizes which cause trouble. Usually, to insure against oversize particles getting into the product, it is necessary to run the classifier in such a manner that many suitable fines are actually returned to the grinding zones with the heavies returned for regrinding. Thus, an undesirable recirculation of satisfactorily ground fines becomes necessary. 7

Furthermore, said centrifuged fines, instead of distributing themselves uniformly upon said bed as they return thereto, may tend to load up near certain nozzles and, due to their poor fiowability, reduce the effectiveness of these certain nozzles.

It has also been found that fines, as well as medium size particles, often tend to adhere to each 2. other in said separator because of the inherent cohesiveness of certain materials or, perhaps, because of a static electrical charge thereon eifected by the rapid circulation of the particles. The resulting groups of small and medium size particles are drawn downwardly by gravity, along with the said large particles, into the said bed. Thus, additional energy must then be expended in separating such particles from each other.

Accordingly, a primary object of this invention isthe provision of a combined pulverizing and classifying machine preserving the advantages of certain earlier machines, especially that disclosed in said Patent No. 1,953,058, while overcoming the disadvantages found in such machines, such as the difficulty encountered in handling medium size particles and agglomerates of small and medium size particles.

A further object of this invention is the provision of a pulverizing and classifying machine, as aforesaid, in which the uniformity of output may be increased without increasin the input energy requirements.

I A further object of this invention is the provision of a pulverizing and classifying machine, as aforesaid, in which large particles are separated from amass of partially comminuted material, pulverized to the required size'and expelled from said machine into a suitable collector with a minimum expenditure of energy.

A further object of this invention is'the provision of a pulverizing and classifying machine, as aforesaid, in which small particles about to be removed to a collector are prevented from improperly returning to the bed of the machine more effectively than has hitherto been possible.

A further object of this invention is the provision of a pulverizing and classifying machine, as

aforesaid, in which small and/or medium particles, which have been raised through a substantial portion of the machine and have then formed an aggalomerated mass of particles, due to mutual adherence, are separated from each other and discharged as fines before they can return to the bed of the machine. I

Other objects and purposes of this invention will become apparent to persons familiar with this type of equipment upon referring to theaccompanying drawings and upon reading the following specification.

In meeting those objects and purposes hereto fore mentioned,-as well as others incidental thereto and associated therewith, I haveprovideda combined pulverizing and; classifying machine comprising a vertically disposed, cylindrical cone supported therewithin adjacent to said An upwardly expanding cone is supported with-.

in said circulation chamber adjacent to and spaced from a horizontally disposed, circular, primary classifying chamber at the upper end thereof. The lower end of the circulation chamber, which holds the partially comminuted material; such as the product of a mechanical grinder, is provided with a plurality of jets through thesidewalls thereof through which a fluid, such as steam, is ejected into said grinding chamber.

The secondary classifier has a coaxial opening in the top thereof and an upwardly expanding top and spaced therefrom. r i

The secondary classifying chamber, the circulation chamber and the primary classifying chamber are all operably connected to a vertical pipe adjacent thereto.

For illustrations of a particular, preferred embodiment of the invention, attention is directed to the accompanying drawings inwhich:

Figure 1 is a brokemside elevation view of the combined pulverizing and classifying machine to which this invention relates.

Figure 2 is a sectional view taken along the line'IIII of Figure 1.

Figure 3 is a sectional view taken along the line III-III of Figure 1. I

Figure 4 is a sectional view of Figure 1 about as taken along the line IV--IV of Figure 3.

, Construction" 'The combination pulverizing and classifying machine 10, hereinafter referred to as the classifier (Figure-l) inasmuch as this invention is only in the classifying portions thereof, is comprised of a circulation housing II and a secondary classifying housing l2 preferably positioned directly above said circulation housing II.

The circulation housing II has a cylindrical,

axially vertical sidewall ['3 supported upon and securedsto a circular base plate M. The upper edge of said wall 13 is partially covered by and secured to a fiat rim l5 (Figures 1, 3 and 4) having a circular, inner opening [6 of less diameter than the inside diameter of the cylindrical sidewall l3. The base plate l4, sidewall l3 andrim l5 define the grinding chamber IT. A cylindrical, axially vertical discharge tube 18 (Figure 1), which may be similar to the discharge tube described and disclosed in the aforementioned Patent No. 1,935,058, is positioned within the lower portion of the grinding chamber l1, coaxial therewith and supported upon the base plate It.

The sidewall l 3 is provided with a circumferential slot (or plurality of small, aligned openings 2| (Figure 4) which preferably extends substantially completely around the cylindrical sidewalls l3 and preferably lies in a plane substantially perpendicular to the axis of the said wall 13. An exterior casing or jacket 22 (Figures 1 and 4) encircles the cylindrical sidewall I 3 enclosing the circumferential slot 2! and providing a circular by-pass chamber 19 between said jacket 22 and said wall 13. The jacket 22 is preferably, but not necessarily, comprised of an upper, downrims, which'a're of less diameter, are secured, as by welding, to the outside of the cylindrical sidewall IS. The said jacket 22 is preferably so positioned that the circumferential slot 21 communicates between the circulation chamber I1 and by-pass chamber 19 just above the circle of contact between the cylindrical sidewall and the lower edge of the lower rim 24.

For the purpose of convenience in description the terms upper or upwardly and lower" or downwardly shall herein be understood to refer to the classifier when positioned and/or operating in its normal manner of use. The terms inner or inwardly and outer or outwardly shall be understood to have reference to the geometric center of the classifier l0, and parts thereof, as herein described.

A materials hopper 25 (Figure 1) for supplying partially comminuted materials to the lower end of said circulation chamber 1 l, is preferably connected by means of the hopper pipe 26 to the said chamber I! at a point intermediate the slot 2| and the baseplate M. It will be clearly understood, however, that the material hopper 25 may be replaced by any other suitable means for supp'lying partially-comminuted materials tothe chamber I! such, for example, as a mechanical grinding machine.

The lower end of the cylindrical sidewall [3 of the classifying housing i2 is provided with a plurality of jets 28 through which an appropriate pulverizing gas, such as steam, may be ejected.

'The jets 28 are preferably aligned with small inlet openings 20 in the discharge tube It. The

partially comminuted material 2T is discharged from the hopper 25 through the pipe 26 into the bottomo'f the chamber ll around the discharge tube l-B, allas set forth in detail in Patent No. 1,953,058. Of course, insofar as the classifier involved in this invention'is concerned, any grinding means discharging a high velocity stream of particle laden gas may be substituted for the grinding means here specifically indicated.

. A cylindrical sleeve 29 i positioned within the circular inner opening 16 of the fiat rim l5 and secured to said flat rim by any suitable means,

such as welding, so that it is substantially coaxial with the cylindrical sidewall 13. The lower portion of the sleeve 29 extends down into the circulating chamber l1 and the loweredge 30 thereof is preferably curved slightly inwardly. A circular 'upper plate 3| is secured to the upper edge of the sleeve 29, as by'welding, said plate having a circular pipe opening 32 therethroug'h coaxial with said sleeve 29. A cent-er pipe 33 extends through said pipe opening 32 coaxial with the cylindrical sleeve 29 and secured to the upper plate 31-, as by welding or brazing. The lower edge of said center pipe 33 preferably extends below the lower edge 30 of the sleeve 29 and the 'upperedge of said center pipe 33 preferably extends above the upper plate. 3| and is wardly curved edge 30 thereof. Thus, a circular .5 primary classifying chamber 36, having a substantially triangular cross-section, is provided and defined by the conical sleeve 35, the cylindrlcal sleeve 29'and' that portion of the upper plate 3| between said cylindrical and conical sleeves 29 mm 35, respectively.- Access to the primary classifying chamber 36 may be gained through the annular slot 31 provided between the lower edge of the conical sleeve 35 and the adjacent wall of the cylindrical sleeve 29 just above the curved edge 36 thereof.

An upwardly expanding lower cone 38 (Figure 4) is 'coaxially supported'within the upper portion of circulation chamber |1 upon the sidewall l3 thereof by any suitable means, such as the support-brackets 39. The cone 38 is provided with a small apex opening 4| through the lower or apex end thereof. The upper, expanded edge 42 of the cone 38, which extends around and above the lower edge 30- of the cylindrical sleeve 29 and is spaced a slight distance therefrom, is also spaced slightly downwardly from the fiat rim I5. Thus, a conically shaped annular passageway 43 isprovided between the upper portion ofthe lower cone 3B and the inwardly curved portion 39 of the cylindrical sleeve 29. It" will also be seen in Figure 4 that the lower end of the center" pipe 33 extends down into the lower cone 38.

The classifying housing |2 (Figure 2), which is-positioned directly above the circulation housing (Figure 1), has a cylindrical sidewall 44 substantially coaxial with the circulation chamber I1 and surrounding cylindrical secondary classifying chamber 45. The classifying housing I2 is spaced upwardly from the circulation housing H by an upwardly expanding conical connection piece 46, whose upper edge is secured to the lower edge of said sidewall 44 as by brazing or welding. The lower end of 'the connection piece 46 is provided with a connection flange 41, substantially similar to the connection flange 34 on the upper end of the center pipe 33 and securable thereto by any suitable means, such as bolts 48.

The top edge of the cylindrical sidewall of the secondary classifying chamber 45 is engaged by and secured to a substantially horizontal, circular top plate 49, which plate is provided with a circular discharge opening substantially coaxially with the cylindrical sidewall 44. A cylin-' drical discharge pipe 52, which is preferably substantially coaxial with the cylindrical sidewalls 44 extends through the discharge opening 5| and is secured to the top plate 49 by any suitable means, such as welding or brazing. The upper end of said discharge pipe 52 may be connected by any suitable means, such as a discharge duct 53 (Figure 1), to an appropriate collection system' (not shown).

An upwardly expanding upper cone 54 is coaxially supported upon the sidewall 44 within the secondary classifying chamber 45 near the upper end thereof by means such as the support brackets 55. The upper edge of said upper cone 54 surrounds and extends above the lower end ofthe discharge pipe 52 and is spaced downwardly from the top plate 49, inwardly from the cylindrical sidewall 44, and outwardly from said discharge pipe 52. 'The upper cone 54 is provided with a small apex opening 56 in the lower end thereof.

- An upwardly expanding, conically shaped baflle ring 51, is coaxially supported within the secondary classifying chamber 45 upon the cylindrlcal sidewalls 44 thereof by means of support brackets 58. The bafiiering 51 is preferably-so positioned that the apex opening 56 lies between the planes defined by the upper and lower'edges' 59 and 6|, respectively, of said 'bafile; ring-51. The upperlarger edge 59 of the baflie ring- 51 is spaced from-the inside surface of the cylindri cal sidewall 44 a very short distance. 1 if A circular inlet opening 62 is'provided in the cylindrical sidewall 44 and the lower edge SI of the baflle ring 51.'- The inlet opening'62 is prefer ably so positioned that its axis is substantially horizontal and tangential with the outermost radial portion of the said secondary classifying chamber 45. The upper end of a by-pass duct 63, whose vertical axis is'preferablysubstantially parallel with the coincident axes of thegrinding chamber l1 and secondary classifying chamber 45, communicates with the chamber 45 through the opening 62 inthe sidewall 44 and is secured thereto as by welding. Thelowerend; of the bypass duct 63,0ommunicates with the circular bypass chamber I!) through a circular outlet open: ing 64 in the upper rim 23 of the jacket 22. The outletop'ening 64 is preferably onsubstantially the same side of the classifier ||v as the inlet opening 62 in the cylindrical sidewall 44.

The byepass duct 63 also communicates withthe circular primary classifying chamber 36 by, means of an intermediate pipe 65 which is operably connected thereto and extends through a- I circular outlet opening 66 in the cylindrical sleeve 29. The outlet opening66 is preferably on the same side of the classifier l9 as the outle opening 64 in the upper rim 23. V

Accordingly, it will be seen that there are several paths of communication. between the grinding chamber l1 and the secondary classifying chamber 35. One of such paths of communication is provided through the lower cone 38, the center pipe 33 and the connection piece 46. Entry to the lower cone-38 from the circulation chamber l1 may be accomplished either through the opening 4| in the lower end of the cone 38 or through the conical passageway 43 at the upper end of the said cone 38. Another path which may be taken by the partially comminuted material 21 is through the slot 2|, by-pass chamber IS, the by-pass duct 63, and the inlet opening 62. Said material can also pass through the conical passageway 43, between the lower cone 38 and the cylindrical sleeve 29, through the lower cone 38, the slot 31, the primary classifying chamber 36, the intermediate pipe 65, the bypass duct 63, and thence into the secondary classifying chamber 45. 7

It will be recognized that damper means 63a, 65a and 33a (Figures 2 and ,4) of any convenient, conventional type may be provided within the by-pass duct 63, the intermediate pipe 65, and the center pipe 33, respectively, for the purpose of controlling the passage of said material 21 through the various above mentioned paths within the scope of this invention. Also, said duct several-well known means, such. as by providing slots '||l inthe wa1ls|35 ofthe circulation chamher-H, plates H on the cone supporting brackets structural material may be used to fabricate the classifier without departing from the substance and scope of this invention. It will be further understood that the exact contour of theoutside of the; device is of; little importance as long as theconipcal and cylindrical'inside contours are retained substantially as described and disclosed.

I Operation 7 I The partially comminuted material. 21 flows from the material'shopper 25 into the bottom ofthe grinding chamber around the discharge tube: |8'. I A suitable: grinding fluid, such as steam; is ejected through the jets 28- into the.

partially comminutedmaterial =2! within at the bottom of the circulating chamber ll. Since the jets 28 are aligned withthe inlet openings 20 in the discharge tube -|8, the material 21 is carried through the openings '20, impacted and shattered,- and swirled up the discharge tube I8 into the circulationch'amber' N. This action is described in detail mthe above mentioned Andrews and Willoughbypatent.

The size of theslot 2|, passageway 43, slit 31 and the diameter of the duct 63. the intermediatepipe B and'the center p'ipe'33 are-balanced as needed so that a strong "flowing stream of the grinding fluid will pass through the slot 2| into the by-pass chamber l9 and the by-pass duct 6-3- into the secondary classifying chamber 45-. This stream picks up and carries to said secondary classifying chamber any fines which maybe sliding down the inside of the wall I3 and would otherwise return to the bed 21 of unground material. The remainder of the material '21 is carried up through the circulation chamber l1 and enters'the lower cone 38 either through theopening 4| in the lower end thereof; or through the annular passageway. r i

In view of the strong upwardfaxial, discharge of material laden gas from the discharge tube l8, there will be little or no swirling ofsaid gas in the circulation chamber |T. However, the gas will circulate therein at high velocities and will, first, impose a substantial oppositiontoheavy particles, hereinafter described; dropping downward out of the cone 38 and. carry some particles upwardly through the opening 4| and, second, carry the remainder of the substantially shattered particles to the top 42 of said cone 38 and into the passageway. The largerparticles will drop out of the gas stream shortly beyond its high velocity zone immediately following dis charge from the discharg tube l8.

The material lad-en gasnow; goes through. the passageway 43 and divides. Part goes to the center and upward through the center pipe 33' and the remainder makes a sharpbend'around the edge 3!] and then goes. upward' throughthe passageway 31.. .Againheaviees will dropout/of the stream, partly bythe slowing. ofthev stream as it crosses the larger areaibetween the passageway 43andth-e center pipe'33; and' partly byflthe heavies being unable tomake the sudden turn around the edge..30'. Theamounts. of gas taking each of these paths is, of course, controlled by the sizes of thepassageways 33 and 65, or by the settings of 'damperstherein. The heavies which drop out will go downlthrough the cone 38, out the opening 4} and back to the bed 2.7. for regrinding. However, any. agglomerates formed by this time will' be broken upby the strong gas stream, andparticles carried thereby, coming upwardthrough the opening 4|. and the. particles resulting f-rom such broken agglomerates, will then rise back upwardly, or continue falling, according to their particularsizes The fines which are, able to round the edge 30 of the cylindrical sleeve 29 then pass through the primary classifying chamber 36 and the pipe 65 intothe duct 63, where they combine with the grinding fluid and fine particles which pass through theslot 2| and the by-pass chamher It. This mass of-fluid and particles then passes through the upper part of the by-pass 6-3 and intothe secondary classifying chamber; Since the duct 63 enters said chamber 45 at a tangent to the radially outer portion thereof, the material entering the chamber through the duct 63- tends; to swirl upwardly with a rotary motion through the chamber 45. I, The oversize particles-and 'agglomerations. which reach the chamber 45, are centrifuged toward the sidewall 44 of the chamber 45- where they are drawn downwardly by gravity along said sidewall through the connection piece 48- and into the center pipe 33. Some finesmay be entrained by said oversize-and agglomerated particles and also move downwardly therewith. Substantially all of the fines which reach the center .pipe 33 in thismanner are entrainedby the fines and grinding fluid passing upwardly through said center pipe. and are thereby pre-- vented from continuing downwardly through said center pipe. The downward movement of the oversize and agglomerated particles is also opposed by the aforementioned fines an'dgrinding fluid passing: upwardly through the center pipe 33 and some of the agglomerationsare broken up with the particles thereof then moving back upward-1y or continuing downwardly according to their individual sizes. Those oversize and agglomerate' particles which drop through thecenter pipe 33 into the cone 38 are subjected to bombardment both by those medium and oversize particles entering said lower' come 38 through the passageway 43' which are unable to pass around the curved edge 30- and' by the gas and material coming upwardly through the opening 4|.

The individual functions of certain of the critical parts of the classifying device willnow' be examined, in order that its principles may be more clearly disclosed. First, assume that the damper 63a is fully closed and the other damper. is open so that the lower half of the conduit 63 becomes inoperative. Underthesecircumstances, no gas will flow out of the-slot 2|. This will not change any of the basic functionsofthe device, but such fines as maybe agglomerated with, or entrained by,,the heavies sliding down the inside wall of the circulation chamber I will be carried on; down to thebed- 21. With gas flowing out of said slot, however,,most of such fines will be entrained thereby and carried up to the secondary classifier as above described. Therefore, the setting of the damper 53a, and/or. the size of the slot 2|, must be so balanced with respect to theccnduits33'and 65 that a strong current of gas will flow out through saidslot.

' Second, assuming that the damper in the cen:- ter' tube'33 is fully closed and the others are open, then there is nothing to effect agitation in the lower part of th secondary classifier, it acts as a mere cyclone and heavy material merely would gather at the bottom thereof; I 1

Third, assuming that the damper inthe pipe 65 is closed and the others are open, then all slot, it should be understood that it could as well be'a'series of'closely spaced, aligned, holes. Although the above mentioned drawings and description apply to one particular, preferred emof the gas from the grinding operation, which gas, excepting for the relatively little that goes out through the slot 2|, is needed to carry the material up and around the upper end of the cone 38, would necessarily go out through the center tube '33. This would create "a stream therethrough of such high velocity that none of the heavies separated out by the secondary classi fier' would be permitted to fall back downwardly out of the secondary classifier. Therefore, enough of such gas is bled out through the pipe 65' to adjust the velocity of the stream through the center tube 33 to carry the fines upwardly but permit the heavies to fall downwardly through it. v l

The initial quantities and velocities of gas are, of course, determined by the requirements'ofconvention impact grinding, which requirements are well known. The sizes and other capacity characteristics of the device are then designed to assure a high enough velocity of gas flow throughout all parts thereof to guard against the existence of dead pockets anywhere therein, and the conduits 63, 65 and 33 are all so designed, and/or their respective dampers adjusted, that there will be a strong flow through each, providing only that the flow through the center tube 33 is not too strong to permit the heavies to return down- Wardly' through it.

Thus when the device is properly adjusted for a given' set of operating conditions, the combined effects of the fines and grinding fluid surging upwardly through the centerpipe 33',the bombardm'en't by the medium and oversize particles in'the' lower cone 38, and the upward movement of fines and grinding fluid through the apex open-' ing 6| tend to break up substantially all'of the agglomerates before they can fall back into the said, bed 21 of partially comminuted material. These effects also strongly inhibit any individual fines from falling back into said bed.

From this it will be seen that oversized particles made up from an agglomeration of fines and/or oversize will be broken up and their fine constituents will be prevented from passing down from the upper cone 54- to the bottom of the grinding chamber l1; first, by the upward movement of fines and grinding fluid through the apex. opening 56;v second, by the upward flow of fines and grinding fluid through the center pipe 33; third, by the impact of mediumand oversized particles entering the lower cone 38 through the passageway 33; fourth, by the upward flow of fines and grinding fluid through the apex opening 4| in the lower cone 38; and fifth, by the ex-' hausting of grinding fluid through the slot 2| in the sidewall of the grinding chamber I'I.

By the time the partially comminuted material 21 reaches the discharge pipe 52 in the top of the secondary'classifying chamber 45 it has been subjected to almost continuous classifying action, which action produces a uniformly fine product which is then exhausted through the discharge While throughout the foregoing the opening 2! has been shown and described as an elongated bodiment of the invention, it is not my intention, implied or otherwise, to eliminate other variations or modifications which do not departfrom the scope of the invention unless specifically statedto the contrary in pended claims.

I claim: 7

1. In a classifying device receiving a stream of high velocity gas laden with particles of a plurality of sizes, the combination: a lower, substantially cylindrical, circulation chamber and means for dividing said chamber into an upper and a lower portion, said upper portion disposed axially of said lower portion and communicating with said lower portion near both the periphery and the center of each of said portions, a centrally located ofitakelextending upwardly from said upper portion; and a primary classifying chamber, annularly arranged surrounding said oiftake and communicating near its periphery with said upper portion of said circulation chamber; a secondary classification chamber constituting a cyclone; means providing communication from said ofitaketo the bottom of said cyclone; means providing communictaion from said primary classification chamber tothe side of said cyclone and discharging tangentially thereinto; offtake means for said cyclone centrally positoned near the'top thereof. i r r 2. In a combined pulverizing and classifying device having upper and lower, vertically disposed, classifying chambers with cylindrical sidewalls, within which a material laden fluid may circulate, and connecting means between said chambers, the improved construction comprising in combination: a horizontal'slot through the sidewall of said lower chamber and a jacket therearound, said slotextending around substantially the entire circumference of said side wall; fluid and "material inlet means associated with the lower end of said lower chamber; an annular chamber horizontally disposed within the upper end of saidlower chamber and having a slot through its bottom opening into said lower chamber; .a. by-pass ductproviding intercommunication between said jacket, said annular chamber and-said upper chamber said duct entering said upper chamber tangentially; and means effecting discharge of' materials laden fluid from the upper end of said upper chamber.

3. ma combined pulverizing and classifying device having upper and lower, vertically disposed, coaxial cylindrical chambers with cylindrical sidewalls within which a material laden fluid may circulate, and connection means providing communication between said upper and lower chambers, the improved construction comprising in combination: a horizontal slot through the sidewall of said lower chamber and an external jacket therearound, said slot extending around a major portion of the circumference of said lower chamber; fluid and material inlet means at the lower end of said lower chamber;

an annular chamber horizontally disposed within the upper end of said lower chamber, having an arcuate peripheral slot through the lower side thereof and having an outer wall spaced inwardly from' the sidewall of said lower chamber; an axially vertical, upwardly expanding funnel'withinrsaid "lower, chamber extending above and around the lower edge of the'outer wall of said the hereinafter ap- 11 annular chamber; ;a discharge pipe coaxial with said upper chamber and providing -:an outlet through the upper end :thereof; and 'a by-ipass duct providing intercommunication between :said jacket, said annular chamber and said upper chamber. a

'4. In a combined pulverizing and classifying machine with upper and. lower, vertically disposed, chambers having coaxial, cylindrical sidewalls within which a gas carrying partially comminuted material may circulate, and a coaxial connecting pipe between said chambers, the improved construction comprising combination: gas and material ,inlet means associated with the lower end of said lower chamberian annular chamber horizontally disposed "within the upper end of saidlowerchamber, encircling the lower end of said connecting pipe and having an outer-wall spaced radially inwardly .from .the sidewall of said lower chamber, said annular Chamberhavinganarcuate peripheral slot throughsits lower side; an axially vertical, upwardly expanding funnel within said lower chamber, the'upperaedge thereof extending-between and spaced from both the outer wall of said annular chamber andsaid lower chamber sidewall thereby effecting-aidouble reversal in upward flow of :said gas from .said lower chamber to said annular chamber; imeans including a coaxial discharge :pipe efiecting discharge of material laden gas from said upper chamber into the area defined by said funnel; and a by-pass duct providing intercommunication between said annular chamber and .said upper chamber.

5. In a combined pulverizing and classifying machine with upper and lower, vertically disposed, chambers having coaxial.;cylindrical sidewalls within which a:gas carrying partially comminuted materialmay circulate, and .a coaxial connecting pipe between said said chambers, :the improved construction-comprising combination: a horizontal slot through the sidewall of said lower chamber-and a jacketaround said sidewall covering'sa'idslot, said'slot extending around the major portion of :the :circumference of'said lower-chamber; gas and material inlet meansassociated with'the lower end of said lower chamber; an annular chamber horizontally disposed within the upper end of said lower chamber, encircling the lower-end ofsaid connecting pipe and having an outer wall spaced radially inwardly from :the sidewall of said lower chamber, said annular chamber having an arcuate' peripheral slot through its lower side; an axially vertical, upwardly expanding lower funnel within said lowers-chamber, the upper edge thereof extending between and spaced from both the outer wall of said annular chamber and said lower chamber sidewall thereby effecting a double reversal in the upward how of said gas'through said lower chamber; an axially =vertical,-upwardly expanding 'fundrical sidewalls within which a gas-carrying'par-- tially comminuted material may circulate, and an elongated opening extending around a major portion of the circumference of said lower chamber; gas inlet means, and means dispersing saidmaterial into gas emitted through-said gas inletmeans, associated with-the lower end of said lower chainber; a. horizontally disposed, annular chamber within the upper end of said lower chamber encircling the lower end of said connection piece and having an outer wall spaced radially inwardly from the sidewall of said lower chamber, said annular chamber having a peripheral slot through its lower side opening into said lower chamber; an axially vertical, upwardly expanding funnel Within said lower chamber extending upwardly around and spaced outwardly from the outer'wall of said annular chamber to form an annularpassageway therebetween; means permitting passage of material laden gas from a point below said funnel to a point thereabove adjacent to said passageway; a by-pass duct providing intercommunication between said jacket, said annular chamber,;andthe lower end of said upper chamber; and means including a discharge pipe efiecting discharge of materials laden gas from the upper-end -,of said upper chamber.

'7. In -a combined pulverizing and classifying machine having upper and lower, vertically disposed, cylindrical, chambers having coaxial cylindrical sidewalls within which agas carrying partially comminuted-material may circulate, artubular member extending upwardly out of saidlower chamber and an upwardly expanding, conical, coaxial connection piece communicating with said upperichamber and the upper end of-said tubular member, the improved construction comprising in combination: an external jacket surrounding the wall -:of :said lower chamber and a narrow, elongated, horizontal slot through said :sidewall betweensaid lower chamber and said jacket, said slot extending-around a major'portion of the circumference of said lower chamber; a jet adapted for gas emission communicating with the'lower end of said lower chamber and means for introducing said material into the path of said jet; a horizontal, annular chamber within the upper end of said lower chamber encircling the lower end .of said connection piece, having a circular peripheral-slot through its lower wall openinginto said lower chamber, and having a radially outer wall spaced inwardly from the sidewall of said lower chamber; an axially vertical, upwardly expanding funnel within said lower chamber ex- -between; .a discharge pipe coaxially extending from the upper end of said upper chamber; and a by-pass ,pipe providing communication between said jacket, said annular chamber and the lower end cf said upperchamber, said by-pass pipe having a horizontal upper portion tangentially disposed to, said upper chamber.

8. In a combined pulverizing and classifying machine for handling a gas carrying par-tially comminuted material, the combination comprising: a'grinding chamber having a vertical cylindrical sidewall, horizontal bottom plate and top rim, and a circumferential slot through said sidewall; a plurality of jets adapted for gas emission communication with the lower end of said grinding chamber and means for introducing said material into the gas streams emitted from said jets; an external jacket surrounding said slot, said slot being adjacent to the lower edge of said jacket; an axially vertical sleeve secured withinsaid rim, extending into said grinding chamber and spaced inwardly from the sidewall thereof; an upper plate covering the upper end of said sleeve and having a pipe opening coaxial therewith; a downwardly expanding, conical sleeve secured under said upper plate coaxially within said cylindrical sleeve, the lower edge of said conical sleeve being spaced from but adjacent to the lower edge of said cylindrical sleeve, thereby providing a horizontal, annular chamber communicating with said grinding chamber; an upwardly expanding funnel coaxially supported with said grinding chamber, the upper edge thereof extending upwardly between and spaced from both said sidewall and said cylindrical sleeve; a center pipe extending through said pipe opening down into said funnel; a vertical cylindrical classifier chamber coaxial with said grinding chamber and having a dis- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,675,941 Lindsay July 3, 1928 1,953,058 Andrews Apr. 3, 1934 2,001,134 Cuppy Mar. 14, 1935 2,188,634 Sturtevant Jan. 30, 1940 FOREIGN PATENTS Number Country Date 443,225 Germany Apr. 16, 192? 

